This disclosure generally relates to a user interface for enabling a user to control a mode of a machine. In particular, this disclosure relates to hardware control devices on a flight deck of an aircraft.
Modern jet transports are equipped with a cockpit mode control panel that interfaces with a flight management system to control the selection and engagement of automatic flight control modes of operation. These automatic flight control modes of operation include, for example, flight level change (FLCH), vertical navigation (VNAV) and lateral navigation (LNAV). The FLCH mode can automatically manage thrust and speed to climb or descend from one altitude to another. The VNAV mode can provide automatic optimized profile control from initial climb through final approach, including adherence to terminal area procedure speed and altitude constraints. The LNAV mode can provide steering to a preprogrammed route including selected terminal area procedures.
The pilot chooses the available modes that will best accomplish the desired vertical flight profile and lateral routing. In most instances, the pilot plans the flight in advance, both laterally and vertically, and preprograms the LNAV and VNAV modes so that the desired flight path will be followed. While preprogrammed flights are advantageous because they reduce the pilot's burden, particularly during takeoff and landing, in practice, rarely can flights be flown as preplanned. For example, rerouting and clearance instructions may be received from air traffic control (ATC) during the flight. These instructions force the pilot to depart from the vertical flight profile and/or the lateral route that was originally planned. In some instances, rerouting and reclearance come far enough in advance to allow the pilot to reprogram the route or profile instructions stored in the memory of an auto flight computer so that the flight management system can remain in the LNAV and VNAV flight control modes. On other occasions, pilots are forced to manually intervene in order to depart from LNAV and VNAV preprogrammed flight paths and comply with ATC instructions in a timely manner.
Intervention-capable flight management systems (FMS) have been developed which allow a pilot to intervene in the operation of the preprogrammed auto flight computer of a flight management system and change the speed and/or flight path of an aircraft in response to ATC instructions. One such system is disclosed in U.S. Pat. No. 4,811,230, and entitled “Intervention Flight Management System.” The intervention FMS disclosed in that patent includes a mode control panel via which the pilot interfaces with an FMS program. The FMS program includes several modules that override the preprogrammed instructions stored in the memory of the auto flight computer when the modules are engaged. In this manner, the FMS allows the pilot to manually intervene and control the auto flight computer and, thus, the aircraft in response to, for example, ATC instructions to change heading, altitude, airspeed or vertical speed. The FMS automatically returns to fully optimized flight along the preprogrammed profile when the intervention is cancelled.
An FMS control panel consists of a multitude of control devices for enabling a pilot to interact with airplane systems and displays. Often these control devices produce a corresponding change to an associated display. For example, turning a knob in one location can change a displayed value in another location. However, some control devices are typically used without looking directly at the controls. To avoid confusion, similarly shaped control devices can be discriminated from each other spatially and sometimes with unique textures. However, operation of the hardware controls on the flight deck is still susceptible to confusion because these control devices do not completely prevent the pilot from reaching for and activating the wrong control device. Furthermore, pilots sometimes only detect the error after the incorrect control device has been used, which produces an unexpected change in the associated display (and sometimes unwanted aircraft performance).
There is a need for an improved system and method that can be used to help avoid such control errors.